Chronic congestive heart failure (CHF), cause by left ventricular dysfunction (LVD), is a major cause of morbidity and mortality. CHF is the major form of cardiovascular disease that is increasing in prevalence, LVD progresses from an asymptomatic phase to a severe symptomatic phase. Recent clinical trials have proven that angiotensin converting enzyme inhibitor reduced mortality, morbidity, and disease progression in asymptomatic patients with objectively measured LVD. However, available estimates of LVD prevalence are based on symptomatic patients, not on objectively measured ventricular function parameters. The distributions of ventricular function parameters in the U.S. population are unknown. Since the prevalence of objectively measured asymptomatic LVD is unknown, the total number of patients with LVD who could benefit from medical therapy is also not known. Furthermore, screening techniques to identify persons with treatable asymptomatic LVD have not been evaluated in a population-based setting. The plasma concentration of n-atrial natriuretic paptide (n-ANP) is a marker for the presence of asymptomatic LVD that may be a valuable screening tool for asymptomatic LVD. The investigators propose a population-based study of the distribution of ventricular function parameters in a probability sample of 1900 adult residents of Olmsted County, MN and, in collaboration with the Strong Heart study, in 1185 adult Northern Plains American Indians. This group of Northern Plains Indians is at increased risk for LVD, having a higher prevalence of cardiovascular disease than the general U.S. population. Subjects will undergo echocardiography to measure ventricular function parameters, as well as a clinical assessment of symptoms, signs and risk factors for LVD. Plasma concentration of n-ANP will be measured in these populations to determine the accuracy of n-ANP as a noninvasive marker for asymptomatic LVD. These studies will 1) provide comparative population-based estimates of ventricular function parameters and LVD in Olmsted County and Northern Plains Indians; 2) provide estimates of the magnitude of the population of patients that could benefit from current therapy; 3) provide current data on risk factors for prevalent CAD in these populations; 4) assess the accuracy of plasma n-ANP in identification of asymptomatic LVD; and 5) provide a foundation upon which future studies of incidence and clinical course of asymptomatic LVD could be based.